This invention relates to new diaminoalkanes and to oxidation colorants containing these compounds.
By virtue of their intensive colors and good fastness properties, so-called oxidation colorants play a prominent role in the coloring of keratin fibers, particularly human hair. Oxidation colorants normally contain oxidation dye precursors, so-called primary intermediates and secondary intermediates. The primary intermediates form the actual dyes with one another or by coupling with one or more secondary intermediates in the presence of oxidizing agents or atmospheric oxygen.
Good oxidation dyes (precursors) are expected to satisfy above all the following requirements: they must form the required color tones with sufficient intensity and fastness during the oxidative coupling reaction. In addition, they must be readily absorbed onto the fibers with no significant differences--particularly in the case of human hair--between damaged and freshly regrown hair (levelling behavior). They must be resistant to light, heat and the effect of chemical reducing agents, for example permanent wave lotions. Finally, if they are used to color hair, they should not overly stain the scalp and, above all, should be toxicologically and dermatologically safe.
The primary intermediates used are, for example, primary aromatic amines containing another free or substituted hydroxy or amino group in the para position or the ortho position, diaminopyridine derivatives, heterocyclic hydrazones, 4-aminopyrazolone derivatives and 2,4,5,6-tetraaminopyrimidine and derivatives thereof.
The secondary intermediates are generally m-phenylenediamine derivatives, naphthols, resorcinol and resorcinol derivatives, pyrazolones, m-aminophenols and pyridine derivatives. With regard to the individual dye components suitable for use in accordance with the invention, reference is specifically made to the Colipa List published by the Industrieverband Korperpflege und Waschmittel, Frankfurt.
In general, natural color tones cannot be obtained with a single secondary intermediate/primary intermediate combination. In practice, therefore, a combination of various primary intermediates and secondary intermediates has to be used to obtain a natural-looking color.
Thus, many intensive blue color tones obtainable with the known primary intermediate/secondary intermediate combinations contain a distinct red component. This red component is a disadvantage, particularly in the case of lighter shades, but also for obtaining natural shades which are intended to have an adequate depth of color and an adequate grey-covering effect.
Accordingly, there is still a need for primary intermediate/secondary intermediate combinations which produce an intensive color in the clear blue range and, more particularly, a pure black tone with no tinges of blue or red.
In addition, the risk of an uneven coloring result, poorer levelling behavior and less favorable fastness properties also increases with increasing number of the oxidation dye precursors used.
Accordingly, there is still a need for new oxidation dye precursors which, in particular, even enable natural colors to be obtained using a smaller number of dye precursors.
Accordingly, the problem addressed by the present invention was to provide new compounds which would satisfy the requirements oxidation dye precursors are expected to meet to a particular degree.